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Factoring Ecological Significance of Sources into Phosphorus Source Apportionment

Cows in pasture near estuary

Models describing the relative contributions of phosphorus (P) from different sources to water bodies (source apportionment) are key tools in determining priorities for mitigation strategies within the River Basin Management Planning process under the Water Framework Directive (WFD). SEPA have made use of a Diffuse Pollution Screening Tool (DSPT) for quantifying and reporting source apportionment within catchments. However, this methodology is simplistic. It is based on total P loads, but not all P loading has the same ecological significance due to differences in the form or timing of the loading. For example, particulate P lost from agricultural sources in the winter does not have the same ecological significance as inputs of P from septic tanks during the warm growing season. This ecological significance needs to be accounted for in P source apportionment.

Project Objectives

  1. Review the key sources of P to flowing waters in the UK, specifically as it pertains to bioavailability.
  2. Develop a holistic and scientifically robust methodology of identifying the most ecologically significant sources of phosphorus in a river waterbody catchment.